Highly luminescent color-selective nanocrystalline materials

Abstract

A nanocrystal capable of light emission includes a nanoparticle having photoluminescence having quantum yields of greater than 30%.

What is claimed is: 
     
       1. A mono disperse population of nanocrystals comprising:
 a plurality of nanocrystal particles, wherein each particle includes a core including a first semiconductor material and an overcoating including a second semiconductor material deposited on the core; 
 wherein the first semiconductor material and the second semiconductor material are different; 
 wherein the monodisperse population emits light in a spectral range of no greater than about 37 nm full width at half max (FWHM); 
 wherein the nanocrystal further comprises an organic layer on the nanocrystal outer surface; and 
 wherein the monodisperse population exhibits photoluminescence having a quantum yield of greater than 30%. 
 
     
     
       2. The coated nanocrystal of  claim 1 , wherein said second semiconductor material includes zinc. 
     
     
       3. A coated nanocrystal capable of light emission, comprising:
 a core comprising a first semiconductor material, said core being a member of a monodisperse particle population; and 
 an overcoating uniformly deposited on the core comprising a second semiconductor material, 
 wherein the first semiconductor material and the second semiconductor material are different, 
 wherein the monodisperse particle population is characterized in that it exhibits no more than about 10% rms deviation in the diameter of the core, and 
 and wherein the monodisperse particle population is characterized in that when irradiated the population emits light in a spectral range of no greater than about 37 nm full width at half max (FWHM) and the coated nanocrystal emits light in a narrow spectral range selected from blue light, green light, yellow light, orange light, or red light. 
 
     
     
       4. The coated nanocrystal of  claim 3 , wherein the spectral range is not greater than about 30 nm full width at half max (FWHM). 
     
     
       5. The coated nanocrystal of  claim 3 , wherein the coated nanocrystal exhibits photoluminescence having quantum yields of greater than 30%. 
     
     
       6. The coated nanocrystal of  claim 3 , wherein the coated nanocrystal exhibits photoluminescence having quantum yields in the range of about 30% to 50%. 
     
     
       7. The coated nanocrystal of  claim 3 , wherein the spectral range is selected from the spectrum in the range of about 470 nm to about 620 nm. 
     
     
       8. The coated nanocrystal of  claim 3 , wherein the monodisperse particle population is characterized in that it exhibits no more than about 5% rms deviation in the diameter of the core. 
     
     
       9. The coated nanocrystal of  claim 3 , wherein the diameter of the core is in the range of about 20 Å to about 125 Å. 
     
     
       10. A coated nanocrystal capable of light emission, comprising:
 a core comprising a first semiconductor material, said core being a member of a monodisperse particle population; and 
 an overcoating uniformly deposited on the core comprising a second semiconductor material, 
 wherein the first semiconductor material and the second semiconductor material are different, 
 and wherein the monodisperse particle population is characterized in that it exhibits no more than about a 10% rms deviation in the diameter of the core. 
 
     
     
       11. The coated nanocrystal of  claim 10 , wherein the coated nanocrystal exhibits less than a 5% rms deviation in diameter of the core. 
     
     
       12. The coated nanocrystal of  claim 10 , wherein the diameter of the core is in the range of about 20 Å to about 125 Å. 
     
     
       13. The coated nanocrystal of  claim 10 , wherein the overcoating comprises greater than about 0 to about 5.3 monolayers of the second semiconductor material. 
     
     
       14. The coated nanocrystal of  claim 13 , wherein the overcoating comprises less than about one monolayer of the second semiconductor material. 
     
     
       15. The coated nanocrystal of  claim 14 , wherein the second semiconductor material is ZnS or ZnSe. 
     
     
       16. The coated nanocrystal of  claim 13 , wherein the overcoating comprises in the range of about one to about two monolayers of the second semiconductor material. 
     
     
       17. The coated nanocrystal of  claim 13 , wherein the second semiconductor material is ZnS or ZnSe. 
     
     
       18. The coated nanocrystal of  claim 3 , wherein the organic layer comprises a moiety selected to provide compatibility with a suspension medium. 
     
     
       19. The coated nanocrystal of  claim 3 , wherein the organic layer comprises a moiety selected to exhibit affinity for the outer surface of the nanocrystal. 
     
     
       20. The coated nanocrystal of  claim 19 , wherein the organic layer comprises a short-chain polymer terminating in a moiety having affinity for a suspending medium. 
     
     
       21. The coated nanocrystal of  claim 3 , wherein the first semiconductor material is selected from the group consisting of CdS, CdSe, CdTe, and mixtures thereof. 
     
     
       22. The coated nanocrystal of  claim 21 , wherein the second semiconductor material is selected from the group consisting of ZnS, ZnSe, CdS, CdSe, and mixtures thereof. 
     
     
       23. The coated nanocrystal of  claim 3 , wherein the second semiconductor material is selected from the group consisting of ZnS, ZnSe, CdS, CdSe, and mixtures thereof. 
     
     
       24. The coated nanocrystal of  claim 3 , wherein the first semiconductor material is CdSe and the second semiconductor material is ZnS. 
     
     
       25. The coated nanocrystal of  claim 24 , wherein the overcoating comprises greater than about 0 to about 5.3 monolayers of the second semiconductor material. 
     
     
       26. The coated nanocrystal of  claim 25 , wherein the overcoating comprises less than about one monolayer of the second semiconductor material. 
     
     
       27. The coated nanocrystal of  claim 26 , wherein the second semiconductor material is ZnS or ZnSe. 
     
     
       28. The coated nanocrystal of  claim 25 , wherein the overcoating comprises in the range of about one to about two monolayers of the second semiconductor material. 
     
     
       29. The coated nanocrystal of  claim 25 , wherein the second semiconductor material is ZnS or ZnSe. 
     
     
       30. The coated nanocrystal of  claim 3 , wherein said coated nanocrystal is a member of a substantially monodisperse particle population. 
     
     
       31. A coated nanocrystal capable of light emission, comprising:
 a core comprising a first semiconductor material, said core being a member of a monodisperse particle population; and 
 an overcoating uniformly deposited on the core comprising a second semiconductor material, wherein the first semiconductor material and the second semiconductor material are the same or different, and wherein the monodisperse particle population is characterized in that when irradiated the population emits light in a spectral range of no greater than about 60 nm full width at half (FWHM), and the coated nanocrystal emits light in a narrow spectral range selected from blue light, green light, yellow light, orange light, and red light. 
 
     
     
       32. The coated nanocrystal of  claim 31 , wherein the monodisperse population emits light in a spectral range of no greater than about 37 nm full width at half max (FWHM) when irradiated. 
     
     
       33. A coated nanocrystal capable of light emission, comprising:
 a core comprising a first semiconductor material, said core being a member of a monodisperse particle population; and 
 an overcoating uniformly deposited on the core comprising a second semiconductor material, wherein the first semiconductor material and the second semiconductor material are the same or different, and wherein the monodisperse particle population is characterized in that when irradiated the population emits light in a spectral range of no greater than about 60 nm full width at halfmax (FWHZW), wherein the coated nanocrystal exhibits photoluminescence having a quantum yield of greater than 30% and the coated nanocrystal emits light in a narrow spectral range selected from blue light, green light, yellow light, orange light, and red light. 
 
     
     
       34. The coated nanocrystal of  claim 33 , wherein the monodisperse population emits light in a spectral range of no greater than about 37 nm full width at half max (FWHM) when irradiated.